Blade play - so what?

T

tirod3

Joined
Jun 27, 2006
Messages
1,700
I see a lot of criticism - and not just about one brand - about blade play in their knife. Basically it's a complaint of low quality that reflects on the maker.

Um, it's a mass produced folding knife intended to be used in the open position? Even fixed knives have flex in the blade, fillet knives are designed that way.

So, is there any specific quantifiable criteria with actual examples to demonstrate what is bad play and what is functionally acceptable? Not just "My expectations were devasted because I bought a POS - waah!"

More like, "I measured x.xxx inches of play x.x inches from the pivot which caused the liner lock ramp to change angle .xx minutes of a degree, changing the normal lock up pressure of x.x ounces of force to .xx, causing the blade to unlock while cutting using the spine as a dull edge through jello. My fingers were severed."

I'm not really looking for lab analysis (and remember, you can't have analysis without anal) - just tired of the uninformed talk. Can we agree on what the specifics are and why?
 
In a locked position, I think it's generally expected to not have any movement in the pivot area, unless of course it was designed for it like a filet knife. I simply don't like blade play, I'm not comfortable with it. When I get a knife that is explicitly designed to move in its locked position, I'll be okay with it. But I don't see myself buying something like that. The simple explaination is, if it's not design to do it, I don't want it.
 
zero is an acceptable amount of blade play, since almost all of my knives exhibit this much, and I don't use those that have more.
 
Blade play may not be a real problem , but it pisses me off in anything over $50.00 .

Chris
 
I would say as long as I'm not able to notice any play, it's fine. None of my folders had any noticeable play when new, though some are/were much more solid feeling than others.

My SERE 2k developed vertical bladeplay and I have to say it is my most neglected folder. I don't usually use it, I don't take it out to play with, it spends most of its time in my drawer. It locks up safe, but the play just annoys me.
 
I've always figured that any blade play in a new knife is unacceptable, horizontal or vertical. Blade flex and blade play are too different things. As a knife is used blade play will develop, sooner or later. If a new knife has blade play, it's a sign of poor quality control, to my way of thinking.
 
Assuming locked position:

If I'm really really picky I have one or two with a small amount of blade play, usually the traditional lockback.

Otherwise I find it unacceptable in any knife over about $50 or so. Also unacceptable in a liner lock or framelock no matter how inexpensive they are.
 
A small amount of blade play does not upset me. Remember.. I said small amount. If its a High Dollar knife... you bet I am upset!
 
A bit of side-to-side blade play in iteself doesn't make a knife completely useless, it's more of an indicator, an indicator of the quality and suitability of materials, the overall quality and care of production, the skill of the maker/worker, and the level of QC.

And while an imperfect knife may be quite functional, my experience indicates that a small amount of blade play can quickly become a large amount with use.

Best Wishes,
-Bob
 
I think Bob W said it best.

It is an issue, and it is an indicator of quality. You can often tighten up the knife to get rid of it, even add a little loctite to keep it away, but it shouldn't be there in the first place on any good quality knife.
 
Another thing about blade play - it is seriously f##king annoying!
Like having a rattle somewhere in your car.

It means something's not right and has gotta get fixed.
 
If I have to torque on a blade pretty good to notice a little blade play I'm not to worried about it. I have a Kershaw Avalanche (one of the original ones) and if I shake it in my handle you can listen to the blade rattle as the locking liner doesn't firmly make contact. Even though it's REALLY loose it doesn't seem like it will fail and close, even with spine wacks. However, it feels really sloppy. I should have sent it back to Kershaw and proably still could, I've just been to lazy to do so. :)

Is there anyway to adjust blade play like this without sending it in? Can I open it up and spin the stop pin? How does the manufacture normally repair play in a liner lock?
 
To my mind, if it's meant to lock in position thats what it should do, NOT wobble on it's pivot either vertically or horizontally. Blade play is not only a sign of poor manufacture but as others have said, it's damned annoying too.
Blade flex is another thing entirely. All blades will flex to some degree. A fillet knife is made to be thin and flexible, a big bowie or camp knife isn't, but it will still flex even if that flex is too small to notice. If it didn't have any flex at all it would be brittle and would snap the first time you put any side pressure on it.
I don't have any "top-end" knives like Sebbies or Striders. The closest I have at the moment is a Buck Strider 880SP. On that, as with any of my other knives, there is NO play once the blade is in the locked position. If I get a knife with play at the pivot once the knife is locked it goes back to the maker for replacemnt or refund, gets fixed or it gets binned.
 
Years ago I knew a collector who collected Italian switchblades and would only accept one with no blade play at all........I always laughed at that as they are not known for tight blades at all.....
 
Blade play is inevitable on mass produced knives. If all components were specified, inspected, selected and assembled to preclude any play, pocket knives would start at $100 and go up from there.

Just a quick question for all the zero play allowed crowd: At what temperature are you determining zero play? Since the pins used in assembly are not generally the same material and heat treat as the blade, or the liners, or the scales, or the backspacer there will be differential expansion/contraction with temperature changes. A folding knife with zero play at 72 degrees may rattle at 10 degrees and stick open or shut at 110. It may not matter if you never go outdoors, but I work outside a lot, and where I live, we have a temperature range from -10 to 110 degrees in an average year.

Sorry about the rant, but I am with the original poster on this subject.
 
you can order a gerber gator for just over 30 dollars and it will lock up tight. tighter than some lockbacks costing much more, as far as up and down play. it used to be common for knives to have loose blades. today I don't think you have to spend a lot to get a folder with a locking blade thats tight, out of the box.
 
I will not tolerate blade play in any of my new knives!! That is just unacceptable to me.
 
Of course I prefer no play like everyone else, but I divide blade play up into two categories. Play that can be detected by wiggling the blade with your hands and play that can be detected during use.

My Buck 110 had a lot more play than my Spyderco Endura. But when using the Endura, the verticle play is noticable anytime you put a decent amount of pressure on the blade. The side to side play on my Buck was very difficult to notice in use. So the Endura's play bothered me more than the Buck's, though each knife has my trust when it comes to their locks.

If an expensive folder of mine develops play, that's fine. If it gets too bad I'll adjust it myself or send it in to factory and pay them to service the knife.
 
yablanowitz said:
Just a quick question for all the zero play allowed crowd: At what temperature are you determining zero play? Since the pins used in assembly are not generally the same material and heat treat as the blade, or the liners, or the scales, or the backspacer there will be differential expansion/contraction with temperature changes. A folding knife with zero play at 72 degrees may rattle at 10 degrees and stick open or shut at 110. It may not matter if you never go outdoors, but I work outside a lot, and where I live, we have a temperature range from -10 to 110 degrees in an average year.
Click to expand...

What knife goes through such a change, that's horrible. I can't think of any tools that undergo such a change over only a 120 degree range. A steel valve with a hardened seat in an aluminum head would leak oil like a sieve at start up and weld itself shut at operating temps if that were so, you have to lose oil pressure for a hell of a lot of rpms before enough heat builds to lock things up. I can't imagine anything that operates at 70 degrees freezing up at 110.
 
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